As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL280 CABIN PRESSURE JUMPED RAPIDLY INTO THE AMBER ON THE EICAS BY THE TIME WE ESTABLISHED A DESCENT IT WAS IN THE RED AND RISING. FOUND KNOB ON MANUAL CONTROLLER STICKING. REMOVED AND REPLACED MANUAL CONTROLLER IAW AMM 21-31-02. OPS CHECKED GOOD. REMOVED AND REPLACED DIGITAL CONTROLLER FOR PRECAUTIONARY PURPOSES.